scholarly journals Trees tell of past climates: but are they speaking less clearly today?

1998 ◽  
Vol 353 (1365) ◽  
pp. 65-73 ◽  
Author(s):  
K. R. Briffa ◽  
F. H Schweingruber ◽  
P. D. Jones ◽  
T. J. Osborn ◽  
I. C. Harris ◽  
...  
Keyword(s):  
Climate Variability ◽  
Tree Growth ◽  
Growth Rates ◽  
Large Scale ◽  
Scale Effects ◽  
Ring Width ◽  
Volcanic Eruptions ◽  
Past Climate ◽  
Tree Ring Data ◽  
Past Climate Variability

The annual growth of trees, as represented by a variety of ring–width, densitometric, or chemical parameters, represents a combined record of different environmental forcings, one of which is climate. Along with climate, relatively large–scale positive growth influences such as hypothesized ‘fertilizationrsquo; due to increased levels of atmospheric carbon dioxide or various nitrogenous compounds, or possibly deleterious effects of ‘acid rain’ or increased ultra–violet radiation, might all be expected to exert some influence on recent tree growth rates. Inferring the details of past climate variability from tree–ring data remains a largely empirical exercise, but one that goes hand–in–hand with the development of techniques that seek to identify and isolate the confounding influence of local and larger–scale non–climatic factors. By judicious sampling, and the use of rigorous statistical procedures, dendroclimatology has provided unique insight into the nature of past climate variability, but most significantly at interannual, decadal, and centennial timescales. Here, examples are shown that illustrate the reconstruction of annually resolved patterns of past summer temperature around the Northern Hemisphere, as well as some more localized reconstructions, but ones which span 1000 years or more. These data provide the means of exploring the possible role of different climate forcings; for example, they provide evidence of the large–scale effects of explosive volcanic eruptions on regional and hemispheric temperatures during the last 400 years. However, a dramatic change in the sensitivity of hemispheric tree–growth to temperature forcing has become apparent during recent decades, and there is additional evidence of major tree–growth (and hence, probably, ecosystem biomass) increases in the northern boreal forests, most clearly over the last century. These possibly anthropogenically related changes in the ecology of tree growth have important implications for modelling future atmospheric CO 2 concentrations. Also, where dendroclimatology is concerned to reconstruct longer (increasingly above centennial) temperature histories, such alterations of ‘normal’ (pre–industrial) tree–growth rates and climate–growth relationships must be accounted for in our attempts to translate the evidence of past tree growth changes.

scholarly journals The 600-mm precipitation isoline distinguishes tree-ring-width responses to climate in China

2018 ◽  
Vol 6 (2) ◽  
pp. 359-368 ◽  
Author(s):  
Yu Liu ◽  
Huiming Song ◽  
Changfeng Sun ◽  
Yi Song ◽  
Qiufang Cai ◽  
...  
Keyword(s):  
Tree Ring ◽  
Large Scale ◽  
Ring Width ◽  
Severity Index ◽  
Annual Precipitation ◽  
Drought Severity ◽  
Climate Variations ◽  
Tree Ring Width ◽  
Past Climate ◽  
Tree Ring Data

AbstractThe numerous temperature and precipitation reconstructions in China based on tree-ring-width data have played significant roles in furthering the understanding of past climate changes. However, the geographical variability in the responses of trees to climate variations in China remains largely undetermined. Here, we describe an important spatial boundary in the response of trees to climate variations, namely the 600-mm annual precipitation isoline. We found that, to the north of this line, tree-ring widths are usually positively correlated with precipitation and negatively correlated with growing-season temperature. To the south of this line, the tree-ring widths respond positively to temperature, and winter half-year temperatures are the main reconstructed parameters, especially on the third topographical step of China. We also found that precipitation reconstructions based on tree-ring data and the Palmer Drought Severity Index almost exclusively fall in the region of the 200- to 600-mm annual precipitation isolines, not other regions. Our findings indicate that, when using multiple tree-ring-width chronologies for large-scale past climate reconstructions, the climatic signal of each tree-ring-width series should be carefully considered.

Reconstruction of maximum temperature on Zhegu Mountain, western Sichuan Plateau (China)

2020 ◽  
Vol 81 ◽  
pp. 1-14
Author(s):  
M Keyimu ◽  
Z Li ◽  
Y Zhao ◽  
Y Dong ◽  
B Fu ◽  
...  
Keyword(s):  
Tree Growth ◽  
Ring Width ◽  
Volcanic Eruptions ◽  
Southwestern China ◽  
Maximum Temperature ◽  
Driving Mechanism ◽  
Western Sichuan ◽  
Relationship Analysis ◽  
Decadal Scale ◽  
Thermal Variability

Historical temperature reconstructions at high altitudes are still insufficient in southwestern China, which is considered one of the most sensitive areas to climate change in the world. Here we developed a tree ring-width chronology of Faxon fir Abies fargesii var. faxoniana at the upper timber line on Zhegu Mountain, Miyaluo Scenic Area, western Sichuan, China. The climate-tree growth relationship analysis indicated temperature as the dominant regulator on radial tree growth in this region. The reconstruction of aggregated maximum temperature (TMX) of autumn and winter for the period 1856-2016 was achieved with a linear regression model that accounted for 43.6% of the actual variability in the common time series (1954-2016). The reconstruction identified 4 warm periods and 3 cold periods. Similarities of warm and cold periods with previously published reconstructions from nearby sites indicated the reliability of our reconstruction. The significant positive correlation between TMX reconstruction and the Asian-Pacific Oscillation index and the Atlantic Multi-decadal Oscillation index suggested a linkage between large-scale climate circulations and the thermal variability at a multi-decadal scale on the western Sichuan Plateau. We also found that solar activity exerted a strong influence on decadal temperature variability in this region. The cold periods were matched well with historical large volcanic eruptions. Our results strengthen the historical climatic information in southwestern China and contribute to further understanding the regional thermal variability as well as its driving mechanism.

Tree growth across the Nepal Himalaya during the last four centuries

2017 ◽  
Vol 41 (4) ◽  
pp. 478-495 ◽  
Author(s):  
UK Thapa ◽  
S St. George ◽  
DK Kharal ◽  
NP Gaire
Keyword(s):  
Tree Ring ◽  
Tree Growth ◽  
Environmental Changes ◽  
Ring Width ◽  
High Elevation ◽  
Forest Growth ◽  
Tree Ring Width ◽  
Early 19Th Century ◽  
Tree Ring Data ◽  
Instrumental Records

The climate of Nepal has changed rapidly over the recent decades, but most instrumental records of weather and hydrology only extend back to the 1980s. Tree rings can provide a longer perspective on recent environmental changes, and since the early 2000s, a new round of field initiatives by international researchers and Nepali scientists have more than doubled the size of the country’s tree-ring network. In this paper, we present a comprehensive analysis of the current tree-ring width network for Nepal, and use this network to estimate changes in forest growth nation-wide during the last four centuries. Ring-width chronologies in Nepal have been developed from 11 tree species, and half of the records span at least 290 years. The Nepal tree-ring width network provides a robust estimate of annual forest growth over roughly the last four centuries, but prior to this point, our mean ring-width composite fluctuates wildly due to low sample replication. Over the last four centuries, two major events are prominent in the all-Nepal composite: (i) a prolonged and widespread growth suppression during the early 1800s; and (ii) heightened growth during the most recent decade. The early 19th century decline in tree growth coincides with two major Indonesian eruptions, and suggests that short-term disturbances related to climate extremes can exert a lasting influence on the vigor of Nepal’s forests. Growth increases since AD 2000 are mainly apparent in high-elevation fir, which may be a consequence of the observed trend towards warmer temperatures, particularly during winter. This synthesis effort should be useful to establish baselines for tree-ring data in Nepal and provide a broader context to evaluate the sensitivity or behavior of this proxy in the central Himalayas.

Bristlecone pine tree rings and volcanic eruptions over the last 5000 yr

2007 ◽  
Vol 67 (1) ◽  
pp. 57-68 ◽  
Author(s):  
Matthew W. Salzer ◽  
Malcolm K. Hughes
Keyword(s):  
Tree Ring ◽  
Ice Core ◽  
Ring Width ◽  
Volcanic Eruptions ◽  
Pine Tree ◽  
Tree Ring Data ◽  
Pinus Longaeva ◽  
Bristlecone Pine ◽  
Ice Core Record ◽  
Pinus Aristata

AbstractMany years of low growth identified in a western USA regional chronology of upper forest border bristlecone pine (Pinus longaeva and Pinus aristata) over the last 5000 yr coincide with known large explosive volcanic eruptions and/or ice core signals of past eruptions. Over the last millennium the agreement between the tree-ring data and volcano/ice-core data is high: years of ring-width minima can be matched with known volcanic eruptions or ice-core volcanic signals in 86% of cases. In previous millennia, while there is substantial concurrence, the agreement decreases with increasing antiquity. Many of the bristlecone pine ring-width minima occurred at the same time as ring-width minima in high latitude trees from northwestern Siberia and/or northern Finland over the past 4000–5000 yr, suggesting climatically-effective events of at least hemispheric scale. In contrast with the ice-core records, the agreement between widely separated tree-ring records does not decrease with increasing antiquity. These data suggest specific intervals when the climate system was or was not particularly sensitive enough to volcanic forcing to affect the trees, and they augment the ice core record in a number of ways: by providing confirmation from an alternative proxy record for volcanic signals, by suggesting alternative dates for eruptions, and by adding to the list of years when volcanic events of global significance were likely, including the mid-2nd-millennium BC eruption of Thera.

scholarly journals Multiproxy records of climate variability for Kamchatka for the past 400 years

2007 ◽  
Vol 3 (1) ◽  
pp. 119-128 ◽  
Author(s):  
O. Solomina ◽  
G. Wiles ◽  
T. Shiraiwa ◽  
R. D'Arrigo
Keyword(s):  
Climate Variability ◽  
Tree Ring ◽  
Ice Core ◽  
Ring Width ◽  
Summer Temperature ◽  
Positive Anomaly ◽  
Temperature Decrease ◽  
Positive Mass ◽  
The Past ◽  
Tree Ring Data

Abstract. Tree ring, ice core and glacial geologic histories for the past several centuries offer an opportunity to characterize climate variability and to identify the key climate parameters forcing glacier expansion in Kamchatka over the past 400 years. A newly developed larch ring-width chronology (AD 1632–2004) is presented that is sensitive to past summer temperature variability. Individual low growth years in the larch record are associated with several known and proposed volcanic events from the Northern Hemisphere. The comparison of ring width minima and those of Melt Feature Index of Ushkovsky ice core helps confirm a 1–3 year dating accuracy~for this ice core series over the late 18th to 20th centuries. Decadal variations of low summer temperatures (tree-ring record) and high annual precipitation (ice core record) are broadly consistent with intervals of positive mass balances measured and estimated at several glaciers in 20th century, and with moraine building. According to the tree-ring data the 1860s–1880s were the longest coldest interval in the last 350 years. The latest part of this period (1880s) coincided with the positive anomaly in accumulation. This coincidence led to a positive mass balance, which is most likely responsible for glacier advances and moraine deposition of the end of 19th-early 20th centuries. As well as in some other high latitude regions (Spitsbergen, Polar Urals, Franz Jozef Land etc.) in Kamchatka these advances marked the last millennium glacial maximum. In full agreement with subsequent summer warming trend, inferred both from instrumental and tree ring data, glacier advances since 1880s have been less extensive. The late 18th century glacier expansion coincides with the inferred summer temperature decrease recorded by the ring width chronology. However, both the advance and the summer temperature decrease were less prominent that in the end of 19th century. Comparisons of the glacier history in Kamchatka with records from Alaska and the Canadian Rockies suggests broadly consistent intervals of glacier expansion and inferred summer cooling during solar irradiance minima.

Disentangling the effects of micro-site ecology on Fennoscandian tree growth

2020 ◽  
Author(s):  
Claudia Hartl ◽  
Elisabeth Düthorn ◽  
Ernesto Tejedor Vargas ◽  
Andreas Kirchhefer ◽  
Mauri Timonen ◽  
...  
Keyword(s):  
Temperature Sensitivity ◽  
Tree Growth ◽  
Growth Rates ◽  
Ring Width ◽  
Peat Bogs ◽  
Northern Fennoscandia ◽  
Climate Reconstructions ◽  
Subfossil Wood ◽  
July Temperature ◽  
Site Ecology

<p>The long tradition in dendroclimatological studies across Fennoscandia is mainly due to the exceptional strong temperature sensitivity of tree growth, as well as the existence of well-preserved subfossil wood in shallow lakes and extent peat bogs. Although some of the world’s advanced multi-millennial-long ring width and density based climate reconstructions have been developed in northern Fennoscandia, it is still unclear if differences in micro-site ecology have been considered sufficiently in previous studies. In order to assess the effects of moist lakeshores versus drier inlands on forest productivity, we present a Fennoscandia-wide network of 44 Scots pine ring width chronologies from 22 locations between 59°-70°N and 16°-31°E. Clustering into coastal settings in northern Norway, continental sites in the lee of the Scands north of the polar circle, and locations south of the polar circle, our network reveals a general dependency of pine growth rates on latitude and July temperature. Differences between moist and dry sites are likely caused by associated effects on soil temperature. While trees at moist micro-sites at western locations exhibit higher growth rates, this pattern inverses under the more continental conditions of the east, where increased ring widths are found at drier sites. In addition to the latitudinal increase in growth sensitivity to July temperature, pines at moist sites tend to show a higher dependency to summer warmth. The highest temperature sensitivity and growth coherency is found in those regions where July temperatures range between 11.5 and 13.5°C and May precipitation totals fall below 100mm. This study not only emphasizes the effects of micro-site ecology on Fennoscandian tree growth, but also provides guidance for the selection of sampling sites for climate reconstructions.</p>

scholarly journals Evolving climate network perspectives on global surface air temperature effects of ENSO and strong volcanic eruptions

2021 ◽  
Author(s):  
Tim Kittel ◽  
Catrin Ciemer ◽  
Nastaran Lotfi ◽  
Thomas Peron ◽  
Francisco Rodrigues ◽  
...  
Keyword(s):  
Climate Variability ◽  
Large Scale ◽  
Southern Oscillation ◽  
Global Climate ◽  
Surface Air Temperature ◽  
Volcanic Eruptions ◽  
Internal Variability ◽  
Hierarchical Organization ◽  
Spatio Temporal ◽  
Global Surface

AbstractEpisodically occurring internal (climatic) and external (non-climatic) disruptions of normal climate variability are known to both affect spatio-temporal patterns of global surface air temperatures (SAT) at time-scales between multiple weeks and several years. The magnitude and spatial manifestation of the corresponding effects depend strongly on the specific type of perturbation and may range from weak spatially coherent yet regionally confined trends to a global reorganization of co-variability due to the excitation or inhibition of certain large-scale teleconnectivity patterns. Here, we employ functional climate network analysis to distinguish qualitatively the global climate responses to different phases of the El Niño–Southern Oscillation (ENSO) from those to the three largest volcanic eruptions since the mid-20th century as the two most prominent types of recurrent climate disruptions. Our results confirm that strong ENSO episodes can cause a temporary breakdown of the normal hierarchical organization of the global SAT field, which is characterized by the simultaneous emergence of consistent regional temperature trends and strong teleconnections. By contrast, the most recent strong volcanic eruptions exhibited primarily regional effects rather than triggering additional long-range teleconnections that would not have been present otherwise. By relying on several complementary network characteristics, our results contribute to a better understanding of climate network properties by differentiating between climate variability reorganization mechanisms associated with internal variability versus such triggered by non-climatic abrupt and localized perturbations.

scholarly journals Early instrumental meteorological observations in Switzerland: 1708–1873

2019 ◽  
Author(s):  
Yuri Brugnara ◽  
Lucas Pfister ◽  
Leonie Villiger ◽  
Christian Rohr ◽  
Francesco Alessandro Isotta ◽  
...  
Keyword(s):  
Climate Variability ◽  
19Th Century ◽  
Central Europe ◽  
Raw Data ◽  
Standard Format ◽  
Past Climate ◽  
The Alps ◽  
Meteorological Observations ◽  
Past Climate Variability

Abstract. We describe a dataset of recently digitised meteorological observations from 40 locations in today's Switzerland, covering the 18th and 19th century. Three fundamental variables – temperature, pressure, and precipitation – are provided in a standard format, after they have been converted into modern units and quality controlled. The raw data produced by the digitisation, often including additional variables and annotations, are also provided. Digitisation was performed by manually typing the data from photographs of the original sources, which were in most cases handwritten weather diaries. These observations will be important for studying past climate variability in Central Europe and in the Alps, although the general scarcity of metadata (e.g., detailed information on the instruments and their exposure) implies that some caution is required when using the data.

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